Process for the manufacture of cement, &amp;c.



L. P. BASSET.

PROCESS FOR THE MANUFACTURE OF CEMENT, 8w.

APPLICATION FILED MAR. 4. 1914.

LM80 Patented Oct 23,1917.

wrrNEs 5Es INVENTOI? J ll/a/f/kfiffl 5,4555?" W A TORNEYS LUCIEN PAULBASSEI, OF PARIS, FRANCE.

PROCESS FOR THE MANUFACTURE OFCEMENT, &o.

To all whom it may concern:

Beit known'that I, LUcmN PAUL BAssET, I

I of 52 Bue Taitbout, in the city of-Paris, Re-

. mainder of the sulfate.

'public of France, for the Manufacture of Cement &c., of

have invented a Process which the following is a full, c ear, and exzielt description.

of manufacture of cement or hydraulic lime "With the simultaneousproduction of sulfur I ous anhydrid or of sulfur, based'on the de--compositionxof sulfate of calcium by'char-E coalor an equivalent reducerand clay.

the sulfate of calcium, it is necessary to add to the mixture of sulfateof calcium and clay, a certain like which tran a 'partof the sulfate,

this sulfid then acting the part of reducer relatively. to the re.-

It is of importance-that the sulfid of calcium, formed as abovestated,be in just sufficien't proportion.

If there is too much sulfid, some of it'remains in the cement andremoves all its value. If, there is not suflicient. of it, there remainsin thecementnon-decomposed sul- 'reduoer, ;a mixture of sulfate and ofsulfid of calcium which s'ufliciently approaches the,

so that the cement obfate which is injurious.

Further, it is impossible to; obtain prec tically, by theaction ofcharcoal or of other theoretic proportion, I tained contains neithersulfid orsulfate for the reductive power of. carbon is not constantbecause 'saidreductive power'depends on the quality of the carbon and ofthe temperature at which-it is caused toact.

The present invention. has for its object a 7 process enabling thecomplete decomposition of the sulfate of calcium to be obtained,'at thesame timeavoidin'g any traces of sulfid remaining in the cement. Thisprocess is cha'racterize'd,=in principle, by the fact that the completedecomposition of the sulfate of calcium isob'tained by means of anexcess ofsulfid of calcium, and this excess of sulfid is then reducedby: oxidation. This oxidation is obtained by the oxygen. of the air. in'excess in the furnace in which the operation is carried on.

This oxidation, in presence of clay, does not transform the sulfid intosulfate; it is formed from the lime and either from sul- Specificationof Letters Patent Application filed March 4, 1914. Serial No. 822,289.

e present invention relates to a process react on the sulfid of calciumguantity of charcoal or the' s orms into sulfid of calcium reactions ofthe new that may be Patented Oct. 23, 1917.

air,- ably to the following reactions 1) CaS+30=CaO+SO i2 cas+o=1o o+s 2In reality intermediary acid, formed according to reaction '(1) can butthis sulfate is again decomposed by the sulfid: which is in excess Toobtaln 'a. complete decomposition. of;

so that the reactions (1) and (2) well represent thefin-al result.

,or from sulfurous 'anhydrid, conform- -The combination of the twofundamental (a) the decomposition of the sulfate by an excess of'sulfid,and (b)- theidecomp'osition of the sulfid in excess by an excess of air,

permits 'of readily obtaining and in practireactions may be produced. Itisvthus thatthe sulfurous process, that is to cal conditions,' cementfree from sulfate and 3 I in effect the first reaction is completeby-means of the excess of sulfid and the second, being very exothermic,is

l readily realized.

, The new process is further characterized by the manner in which theexcess of sulfid is obtained which is necessary for producing thedecomposition of-the calcium sulfate.

This excess of sulfid is obtained by adding an excess of charcoal or thelike to the paste formed by the mixture of sulfate of calcium and clay.

In order then to destroy the excess of sulmeans of oxygen, as aboveindicated,-

the furnace should, in the roasting zone,

work in an oxidizing The accompanying example only, and in adiagrammatic way, the arrangement of the furnace.

Figure 1 is a longitudinal section; Figs. 2, 2, 3 and fshow variouspositions occupied by the twyers.

atmosphere.

drawing shows-as an This furnace, shown in Fig. 1 of the drawlngcomprises two distinct parts a and b.

The part a-constitutes a reducing zone and the part b an'oxidizing zone.

This furnace consists of arotating cylinder 0 of great length, the endsof which enter two fixed chambers d and e..

In the first chamber is arranged a chute f conveying the paste, formedby the mixture of clay, sulfate of calcium and a little I charcoal orthe like anda discharging concoal or the like, in powder carried along.

ductor g openinginto the chimney.

- In the second chamber the discharge for the treated products is shownat h.

A twyer i serves as an injector, either of oxid of carbon or otherreducer, or of charby a little air under pressure, or preferably, by afraction of the gases of combustion taken fromd, still hot and deprivedof oxygen. This charcoal or the like. burning in i the flame, absorbsthe oxygen from the air -z' theatmosphere is reducing; under the ac-'-tion of the oxid of carbon contained in the.

in excess and furnishes oxid of carbon.

011 the other. hand, air in excess is introduced by a twiyer j.

The paste formed by the mixture, either dry or moist, of sulfate ofcalcium, clay-and a little charcoal or the like, is introduced by thechute fand falls intothe end. of the furnace,

proportion as it advances it encounters higher and higher temperatures.

In all thezone a to the right of thetwyer gases of the furnace and thatofthe charcoal or the like contained in the-paste, a certain quantity ofsulfate is transformed into sulfid and this sulfid is found in excess.

When the matters treated pass to .the left of 2' they encounter anoxidizing atmosphere which, provokes-the decomposition of the in inverseirection as indicated by the ar rows 2. 7

According to the quantity of charcoal or the-like injected by the-twyerz the furnace I gases have, in the part'a, greateror less reducingpower. This quantity of charcoal or the like can be readily modified, incourse of working, and the compositionof the furnace gases canberegulated at willcording to the nature of the'latter.

By delivering sufiicient charcoal or the like at i the charcoal or thelike mixed with the paste may even be omitted.

The position of the twyer 2' may be varied and consequently the-relativeimportance of the zones at and b may be modified. Figs. 2, 3 and 4represent diagrammatically the possible positions of the twyers i and j.

In the case of Fig. 2 the twyers i and j are concentrically shown. Theymight just as well be placed one next to the other as shown in Fig. 2The furnace flame is reductive, .as also all the atmosphere of the gasesare insu then it advances from the rightend of the furnace toward itsleft end. In

This result is important, the reducing power of the charcoal or the likevariesacfurnace after'the twyer. The working of the furnace in this caseis more delicate than in the. other cases, the reducing power of thegases should be exactly regulated because the reductive atmosphere ofthefurnace must takefrom the mass ofcalcium. sulfate a definitequantity'ofoxygen if the ciently reductive, there remains some sulfate,and if they are too res ductiv'e-an excess of sulfid will beformedremaining inthe cement] I The; arrangement ofFig. 4 differs fromthat'sho'wn in Fig. 1 only in the-:shapeof the furnace, which-iscomposed of. two dis- I tinctive parts at different/levels connected byan" inclined conduit, and at the entrance. of which are respectivelymounted the two twyers 2', j. -The reactions, causedby the arrangementshown in Fig. 1 are also'c'aused in a rigorous manner by the arrangementshown in Fig. .4. y

-With'the-new process and the 'newapparatus, there can be recovered asby-product,

" either sulfurous acid'or sulfur. i

- In the case of sulfur, the dissociation is effected according to thefollowing reactions 3so.ca.+cas=4cao+4so.

SO +2CO=2CO +S The combination ofthese two reactions considerablyfacilitates the dissociation of the sulfate of calcium, as the sulfurousanhydrid. liberated abeing .'Joroken up into.

sulfur as and in proportion as it is -produced by the oxid of carbonormore generally by the reducer employed, inverse reaction isrenderedimpossible' This combinationof these two reactions takes placein the zone a according to thereductivity of the atmosphere, thetransformation of the sulfurous acid into sulfur is total or partial.

'Applicantsfurnace further enables the transformation of all thesulfurous acid into sulfur to be readily obtained, as the reducingpowercan be'readily regulated.

. If it is required toobtain sulfurous acid entirelyjfree from sulfurand from carbonic oxid, air is introduced into the furnace, at

a'suitable-place so as to completely oxidize the gases.

Generally speaking, the new process can be carried into effect in "anyfurnace in which are provided two zones of difierent oxidizing power.

Thus the first zone, called dissociation zone, can be'reducing and thesecond, called roasting. zone, oxidizing, or the first zone can beneutral and the second rather highly oxidizing, or again the firstslightly oxidizmg and the second highly oxidizing.

According as the furnace happens to be in one of the three above cases,the proportion of charcoal is modified accordingly "able to have first areducing atmosphere at the entrance of the furnace (which is then thedissociation zone) andmoderately oxidizing in the second zone.

If, on the contrary, a large excess of charcoal or the like is added, itis advisable to have a furnace with an oxidizing atmosphere from end toend, slightly oxidizing at the entrance, in the dissociation zone, .and

highly oxidizing in the second zone. In this case, the mass being of ahighly reduc ing nature, the oxidizing influence of the atmosphere, inthe'first zone, does not pre vent the whole of the'conditions oftreatment to be .at. this moment reducing conditions.

As will be understood, it is necessary to consider at every moment thewhole of the conditions resulting from the nature of the mass treatedand from the nature of the furnace atmosphere and by suitably regulatingeither the one or the other, it is possible, on the one hand, to vary insufliclently large .proportions the quantity of charcoal or the likeadded to the mixture treated and, on the other hand,.to utilize anyfurnace having tWo 291168 of diflerent oxidizing power, as stated above.I

By varying the composition of the mixture or the nature .of theatmosphere of the furnace, as explained above, it is possible to go onup to limit cases. Thus by diminishing the quantity of charcoal or byincreasing the reducing power of the furnace atmosphere, the extremecase would be 1 reached Where the charcoal would be com pletely doneaway with. The reaction set forth at the beginning of the presentspecification, that is to say the formation of an excess of sulfid, isstill possible. However,

it is to be understood that these limit cases are, usually, lessadvantageous than the normal case set forth at the beginning of thespecification.

In the same way, it is possible to vary the proportion of charcoal, asjust explained,

even by continuing up to the limit case where the charcoal is done awaywith; it is also possible to vary the fproportion of clay for obtainingcements o continuing up to limit sible to manufacture quick limeor slag.

In the case where the clay is done away with and where quick lime isobtained, this lime can afterward be mixed, after slaking,

cium sulfate in the production of sulfurous acid, consisting in liquidplaster and clay, proportional with the quantity of oxygen in treatingthe remainder of the calcium sulfate by means of an excess of thissulfid,

"sulfurous acid, consisting in a different quality; by 'd cases, it willbe poswith clay, for obtaining. hydraulic lime,

Portland cement, or slag, according to the proportions.

If, on the contrary, used, the slag obtained (silicoaluminate ofcalcium) is mixed with lime or carbonate of lime in suitable proportionsfor obtaining, by a new roasting, Portland cement or hydrauliclime.

If the slag has been granulated, its sim le mixture with cement.

Claims:

1-.- A proces of manufacturing cement or hydraulic lime by thedecomposition of calpresence of clay, with an excess of clay is treatingthe calcium sulfate by an excess of calcium sulfid and in decomposingthe latter.

by oxidation.

2. A process of manufacturing cement or hydraulic lime by thedecomposition of calcium sulfate in the production of sulfurous acid,consisting in reducing a part of the calcuim sulfate to be treated tocalcium sulfid by means of an exj cess of carbon added to the mixture ofplaster and clay,in treating the remainder of the calcium sulfate by anexcess of calcium sulfid, thus obtained, and in decomposing said sulfidby oxidation. I

3. A process of manufacturing cement and hydraulic lime 'bydecomposition of plaster in the presence of clay, tion of sulfurous.acid, consisting inreducing in a furnace a partOf the calcium sulfate tobe treated to calcium sulfid by means of an excess of carbon added tothe mixture of this excess of carbon being travelingin the furnace,

and in decomposing this sulfid by an oxidation.

4. A process for the manufacture of ce ment and hydraulic lime withroduction of ding an excess ofcarbon to a mixture of sulfate of calciumand clay, subjecting the mixture to heat in a furnace, the excess ofcarbon being proportional to the quantity of oxygen .tra'vel slaked limewill give s ag" presence of clay, with w th produc-- ing through thefurnace, reducing a portion I of the sulfate of calciumby the excess ofcarbon to obtain an excess of sulfid of calcium, decomposing theremainder of the sulfate of calcium by means of the excessof sulfid ofcalcium, and subsequentlysubjecting the mixture to the action ofatmospheric air in excess to decompose the sulfid by oxiation.

5 In a process for the manufacture of cement and hydraulic lime,subjecting a mixture of sulfate of calcium and clay to heat in thepresence of a reducing agent thereby decomposing a portion of thesulfate and obtaining sulfid of calcium in excess, decomposing theremainder of the sulfate of calcium by means .of the excess of sulfid ofcalcium, subsequently decomposing the sulfid of calcium by oxidation,and finally obtaining sulfurous acid as a by-product of the reduction.

' 6. A process of manufacturing cement or hydraulic lime by thedecomposition of plaster in the presence of clay with the production ofsulfurous acid consisting,in reducing in a furnace a part of the calciumsulfate to be treated to calcium sulfid by means of an excess of carbonadded to the plaster, this excess of carbon being proportional with thequantity of oxygen traveling through the furnace, in treating thecalcium sulfate by an excess of calcium sulfid thus obtained,indecomposing this sulfid by an oxidation, in causing the lime obtained toact immediately in the presence of the clay and in subjecting the,mixture to a second roasting.

7. A process of manufacturing cement and'hydraulic lime by thedecomposition of plaster in .the presence of. clay, with production ofsulfurous acid, consisting-in reducing in a furnace a part of thecalcium sulfate to be treated to calcium sulfid by means of an excess ofcarbon added to the plaster, this excess of carbon being proportionalwith the quantity of oxygen traveling through the furnace,in treatingthe re- 'mainder of the calcium sulfate by means :of

an excess of calcium sulfid thus obtained, in the presence of an excessof clay to com pletelydecompose the calcium sulfate, in decomposing thissulfid by an oxidation, in

causing the slag resulting from the decomposition of the plaster in thepresence of 'an excess of clay to act immediately on the lime, and insubjecting the same to a second roast- 2 5. A process for themanufacture of ca ment by the decomposition of the plaster .in

the presence of clay with the production of sulfurous acidconsisting'in. reducing in a furnace a part of the calcium sulfate to betreated to sulfid of calcium by means of an excess of carbon added tothe plaster, this excess of carbon being proportional to the quantity ofoxygen traveling through the furnace, in treating the remainder of thecalcium sulfate by means of an excess of calcium sulfid thus obtained,in the presence of an excess of c1ay,-in decomposing this sulfid byoxidation, and in mixing immediately the slag resulting from thedecomposition of the plaster in the presence of an excess of clay withslaked lime for obtaining a slag.

9. In a process for the manufacture of ce- I cement and hydraulic limeby means of sulfate of calcium and clay, which consists in treating amixture of sulfate of calcium and clay to form sulfid of calcium, thendecomposing the sulfid of calcium by oxidation to form oxid of calcium,and causing a reaction between the oxid of calcium and clay.

11. In a process for the manufacturing of cement and hydraulic lime bythe decomposition of sulfate of calcium in presence of clay, whichconsists in subjecting the sulfate of calcium and clay to the action ofheat, forming calcium sulfid out of the sulfate and then decomposing thesulfid by oxida-' tion.

12. The herein described steps in a process for the manufacture ofcement and bydraulic lime by the decomposition of sulfate of calcium inpresence of clay, which consists in subjecting the sulfate of calciumand clay to the action of heat, converting the sulfate into asulfidand-then-decomposingdthe so-formed sulfid to form calcium 0x1 13. Theherein described steps in a process for the manufacture of cement andhydraulic lime by the decomposition of sulfate of calcium in thepresence of clay, which consists in subjecting the sulfate of calciumand clay to the action of heat, converting the sulfate of calcium into asulfid by means of calcium sulfid and then decomposing the so-formedsulfid to form calcium LUCIEN .PAUL BASSET.

Witnesses:

HANSON C. CoxE, RENE THIRIOT.

